MEDIUM

CVE-2021-33197

CVSS v3

5.3

MEDIUM

EPSS Score

2.3 %

exploit probability, as of 2026-10-19

CISA KEV

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

golangBitnamiall versions · fixed in 1.15.13
stdlibGoall versions · fixed in 1.15.13
buildahAlmaLinux:9all versions · fixed in 1:1.27.0-2.el9and 1 other package
delveAlmaLinux:8all versions · fixed in 1.6.0-1.module_el8.5.0+2604+960c7771
grafanaAlmaLinux:8all versions · fixed in 7.5.9-4.el8
podmanAlmaLinux:9all versions · fixed in 2:4.2.0-3.el9and 5 other packages

Vendor advisories

CVE-2021-33197 Red Hat Product Security817 products fixed · 91 known affected
golang: net/http/httputil: ReverseProxy forwards connection headers if first one is empty
knative-serving as a component of OpenShift Serverless · servicemesh as a component of OpenShift Service Mesh 2.0 · servicemesh-grafana as a component of OpenShift Service Mesh 2.0
RHSA-2022:8008 Red Hat Product Security21 products fixed
Red Hat Security Advisory: buildah security and bug fix update
RHSA-2022:7954 Red Hat Product Security46 products fixed
Red Hat Security Advisory: podman security and bug fix update
RHSA-2022:1402 Red Hat Product Security6 products fixed
Red Hat Security Advisory: OpenShift Virtualization 2.6.10 RPMs security and bug fix update
RHSA-2022:1329 Red Hat Product Security6 products fixed
Red Hat Security Advisory: OpenShift Virtualization 4.8.5 RPMs security update
RHSA-2022:0577 Red Hat Product Security2 products fixed
Red Hat Security Advisory: Windows Container Support for Red Hat OpenShift 5.0.0 [security update]

23 more advisories

Full record on NVD

Description

In Go before 1.15.13 and 1.16.x before 1.16.5, some configurations of ReverseProxy (from net/http/httputil) result in a situation where an attacker is able to drop arbitrary headers.

Technical details

Published: 2021-08-02

Frequently asked questions

What is CVE-2021-33197?

In Go before 1.15.13 and 1.16.x before 1.16.5, some configurations of ReverseProxy (from net/http/httputil) result in a situation where an attacker is able to drop arbitrary headers.

Is CVE-2021-33197 actively exploited?

Active exploitation of CVE-2021-33197 has not been confirmed. Its EPSS score was 2.3% on 2026-10-19, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-33197?

CVE-2021-33197 has a CVSS v3 base score of 5.3 (MEDIUM severity).

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